Sources of ω3 Fatty Acids in Arctic Diets and Their Effects on Red Cell and Breast Milk Fatty Acids in Canadian Inuit

Abstract

Considerable interest has been given to the relationship of dietary ω3 fatty acids, particularly eicosapentaenoic acid (20:5ω3), to human disease since the publication of epidaemiological data demonstrating a relationship in Greenland Eskimo between a diet containing large amounts of marine lipid and a low incidence of ischaemic heart disease1 – 5. The ensuing flurry of clinical and research studies have focused almost exclusively on diets high in fish or supplemented with fish oil concentrates, and the biochemistry of 20:5ω3, particularly as it relates to the ω6 fatty acid arachidonic acid (20:4ω6) and eicosanoid metabolism. These studies have shown that incorporation of dietary ω3 fatty acids, largely at the expense of ω6 fatty acids, into membrane structural lipid results in altered membrane physical properties and membrane-dependent biochemical and physiological processes6. Substantial knowledge on the function of 20:4ω6 and 20:5ω3 as substrates for eicosanoid synthesis has been gained, although much remains to be learnt on the specific relationship between diet and the tissue fatty acids pools utilized for eicosanoid production in vivo7. The epidaemiological association between a high marine lipid intake and a low prevalence of ischaemic heart disease also directed attention to the possible effects of ω3 fatty acids on cholesterol and triacylglycerol metabolism in both normo- and hyper-lipidaemia8. Despite considerable research, the efficacy of dietary fish in reducing disease incidence remains uncertain. Both a reduction9,10 and no reduction11,12 in ischaemic heart disease has been described in free-living populations with a high dietary fish intake.

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